Table of contents

1. Introduction to Biochemistry4h 34m
2. Water3h 23m
3. Amino Acids8h 10m
4. Protein Structure10h 4m
5. Protein Techniques14h 5m
6. Enzymes and Enzyme Kinetics13h 38m
7. Enzyme Inhibition and Regulation 8h 42m
8. Protein Function 9h 41m
9. Carbohydrates7h 49m
10. Lipids5h 49m
11. Biological Membranes and Transport 6h 37m
12. Biosignaling9h 45m
Review 1: Nucleic Acids, Lipids, & Membranes2h 47m
Review 2: Biosignaling, Glycolysis, Gluconeogenesis, & PP-Pathway3h 12m
Review 3: Pyruvate & Fatty Acid Oxidation, Citric Acid Cycle, & Glycogen Metabolism2h 26m
Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation1h 48m

12. Biosignaling

Stimulatory Adenylate Cyclase GPCR Signaling

Biochemistry

12. Biosignaling

Stimulatory Adenylate Cyclase GPCR Signaling

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Multiple Choice

In response to a ligand binding a GPCR, a particular G protein (G _s) activates adenylate cyclase. If a cell has a mutation where the G protein can no longer hydrolyze GTP, which of the following would be the result?

Cellular levels of cAMP would go down in response to ligand binding.

Cellular levels of cAMP would go up independent of ligand binding.

The ligand would not be able to bind to the receptor.

Cellular levels of cAMP would not change.

Adenylate Cyclase would always remain inactive.

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Verified step by step guidance

Understand the role of G proteins in signal transduction: G proteins are molecular switches that activate or deactivate signaling pathways in response to ligand binding to GPCRs (G protein-coupled receptors).

Recognize the function of G_s protein: G_s is a type of G protein that, when activated, stimulates adenylate cyclase, leading to the production of cyclic AMP (cAMP) from ATP.

Consider the impact of GTP hydrolysis: Normally, G proteins hydrolyze GTP to GDP, which turns off the signal. If a mutation prevents GTP hydrolysis, the G protein remains active longer than usual.

Analyze the consequences of a non-hydrolyzing G protein: Without GTP hydrolysis, G_s remains active, continuously stimulating adenylate cyclase, leading to increased levels of cAMP regardless of ligand binding.

Conclude the effect on cellular cAMP levels: Since adenylate cyclase is persistently activated, cellular levels of cAMP would rise independently of ligand binding, as the G protein cannot turn off the signal.